Integrated structure of multilayer flow microchannel and method for operating multilayer flow using it

ABSTRACT

An integrated structure of multilayer flow microchannel, which comprises a plurality of microchannels in which parallel multilayer flow that involves the interface of fluids is formed, arranged on various positions of a substrate, wherein each of the multilayer flow microchannels is communicated with another multilayer flow microchannel. A plurality of unit operations can be carried out continuously with high efficiency on a microchip, enabling high-degree microanalysis or precise chemical synthesis using the highly integrated structure of multilayer flow microchannel.

TECHNICAL FIELD

[0001] The invention of the present application relates to an integratedstructure of multilayer flow microchannel and a method for operating amultilayer flow by using the integrated structure of multilayer flowmicrochannel.

[0002] More specifically, the invention of the present applicationrelates to a highly integrated multilayer flow microchannel structurethat enables high accuracy microanalysis and precise chemical synthesisto be performed on a microchip by continuous operation with highefficiency. The invention also relates to physiochemical and chemicalmethods for fine operation that use the highly integrated multilayerflow microchannel structure.

BACKGROUND ART

[0003] In recent years, studies on a technique known as p-TAS (MicroTotal Analysis Systems) or Lab-on-a-Chip, in which chemical operationsor physiochemical operations are integrated onto a substrate of a fewsquare centimeters, has rapidly prevailed.

[0004] However, in such techniques, integration on a microscopicsubstrate, or chip is not easy. Unlike DNA chips, wherein probes for thedetection of biomolecules are immobilized, for μ-TAS or Lab-on-a-Chip,high degree integration of minute channels (microchannels) for handlingliquid samples is difficult, and thus, serializing operations of complexchemical processes is not easy.

[0005] Under these conditions, the present inventors have explored theintegration of complex chemical processes by combining various UnitChemical Operations, and have previously made several proposals. In suchexplorations, the present inventors have made it an object to enable thehandling of multilayer flow, as highly controlled fluid, within amicrochannel, and to integrate such multilayer flow onto a microchip.

[0006] Hence, in consideration of the aforementioned background, anobject of the present invention is to provide a highly integratedstructure of multilayer flow microchannel, which enables the efficientperformance of high-accuracy microanalysis, precise chemical synthesisor the like by continuous operation of a plurality of unit operations ona microchip; further, another object of the present invention is toprovide an operation method that utilizes this structure.

DISCLOSURE OF THE INVENTION

[0007] In order to achieve the above-described objects, the invention ofthe present application provides, firstly, an integrated structure ofmultilayer flow microchannel, which comprises a plurality ofmicrochannels in which parallel multilayer flow that involves theinterface of fluids is formed, arranged on various positions of asubstrate, wherein each of the multilayer flow microchannels iscommunicated with another multilayer flow microchannel.

[0008] Secondly, the invention of the present application provides theintegrated structure of multilayer flow microchannel, wherein theplurality of multilayer flow microchannels are arranged on a surface ofone substrate and each multilayer flow microchannel communicate withanother multilayer flow microchannel by way of a guide microchannel thatidentifies a specific fluid. Thirdly, the invention of the presentapplication provides the integrated structure of multilayer flowmicrochannel, wherein a plurality of substrates are laminated, and themultilayer flow microchannels are arranged on surfaces of differentsubstrates, and wherein the vertically configured multilayer flowmicrochannels communicate with another multilayer flow microchannelthrough a vertically penetrating guide hole for transporting a fluid.Fourthly, the invention of the present application provides theintegrated structure of multilayer flow microchannel, comprising aplurality of substrates that are laminated, wherein a channel forsupplying a fluid to the multilayer flow microchannel and a channel fordischarging a fluid from the multilayer flow microchannel are eacharranged on the surface of the same or different substrate as that onwhich the multilayer flow microchannel are arranged.

[0009] Fifthly, the invention of the present application provides theintegrated structure of multilayer flow microchannel, wherein aplurality of multilayer flow microchannels are configured as differentunit operation regions. Sixthly, the invention of the presentapplication provides the integrated structure of multilayer flowmicrochannel of any one of claims 1 to 5, wherein at least onemultilayer flow microchannel is configured as an analysis region.

[0010] Seventhly, the invention of the present application provides amethod for multilayer flow operation, which comprises the use of any ofthe above-described integrated structure of multilayer flowmicrochannel. Eighthly, the invention of the present applicationprovides the method for multilayer flow operation, wherein a multilayerflow involving gas/liquid fluid interface is formed within themultilayer flow microchannel. Ninthly, the invention of the presentapplication provides the method for operating multilayer flow, wherein amultilayer flow involving three or more fluid layers is formed withinthe multilayer flow microchannel.

[0011] Tenthly, the invention of the present application provides amethod for multilayer flow operation, which comprises the formation of amultilayer flow of three or more layers involving interfaces of fluidswithin microchannels arranged on a substrate. And eleventhly, theinvention of the present application provides a method for multilayerflow operation, which comprises performing a plurality of unitoperations by way of the interface of fluids in a multilayer flow ofthree or more layers involving interfaces of fluids.

BRIEF DESCRIPTION OF DRAWINGS

[0012]FIG. 1 is an illustration that exemplifies an overview of thepresent invention.

[0013]FIG. 2 is an illustration that exemplifies an overview of thepresent invention that is different from FIG. 1.

[0014]FIG. 3 is a schematic sectional view that exemplifies athree-dimensional configuration.

[0015]FIG. 4 is a planar view showing the structure of FIG. 4(A).

[0016]FIG. 5 is a sectional view that exemplifies the guide structure atthe bottom of a microchannel.

[0017]FIG. 6 is a view and photograph each showing the formation of amultilayer flow within a microchannel.

[0018]FIG. 7 is a graph showing the result of the detection of Co(II)using a thermal lens microscope in Example 1.

[0019]FIG. 8 is a graph showing the result of the detection of Co(II) ofdifferent concentrations.

[0020]FIG. 9 is a graph showing the relationship between theconcentration of Co(II) and the signal intensity detected by the thermallens microscope.

[0021]FIG. 10(A) is a planar view of the microchannel pattern used inExample 2 and FIGS. 10(B), 10(C), 10(D). 10(E), 10(F) and 10(G) aremicrographs that illustrate the formation of multilayer flow.

[0022]FIG. 11(A) is a schematic planar view of the microchannel ofExample 3. FIG. 11(B) is a graph showing the measurement result of theintensity of TLM detected.

[0023]FIG. 12 is a micrograph illustrating the result obtained inExample 4.

[0024] The numbers in the drawings refer to the following:

[0025]1, 2 Multilayer flow microchannel

[0026]1A, 2A Liquid supplying channel

[0027]1B, 2B Liquid discharging channel

[0028]3 Guide microchannel

[0029]4 Multilayer flow microchannel

[0030]5 Guide hole

BEST MODE FOR CARRYING OUT THE INVENTION

[0031] The invention of the present application comprises theabove-described characteristics. Hereinafter, further embodiment of theinvention will be described.

[0032] The most important feature among the first to ninth aspects ofthe present invention is that a plurality of microchannels, wherein amultilayer flow that involves the interface of fluid is formed, arearranged on various positions of a substrate, and that each of themultilayer flow microchannels communicate with another multilayer flowmicrochannel.

[0033] Here, the substrate on which a plurality of multilayer flowmicrochannels are arranged may be a single substrate or a plurality ofsubstrates laminated together. When a plurality of substrates arelaminated with each other, one multilayer flow microchannel may bearranged on one substrate and as a whole, in other words, as anintegrated structure, may constitute a substrate comprising a pluralityof multilayer flow microchips

[0034] The multilayer flow microchannels arranged on various positionsmay each be adapted to perform a single type of unit operation such assolvent extraction, or, alternatively, may each be adapted to performdifferent types of unit operations such as solvent extraction and asubsequent operation for chemical reaction. Further, each of themultilayer flow microchannels may be structured so as to enable theperformance of a plurality of unit operations within a single multilayerflow microchannel. In either of the above-described multilayer flowmicrochannels, a parallel multilayer flow of two or more layers areformed.

[0035] The type of unit operation is not particularly restricted, andmay be any physiochemical or chemical unit operation (including unitreactions) of various types. Needless to say, the unit operationincludes operations for analysis or measurement.

[0036] In the invention of the present application, the multilayer flowinside the microchannel may form a liquid/liquid interface or agas/liquid interface.

[0037] The most significant feature of the present invention lies inthat three or more layers of parallel multilayer flow is formed, asdescribed in the ninth, tenth and eleventh aspects of the invention.

[0038] The present invention may be described, for example by referringto the attached FIG. 1 and FIG. 2. First, as shown in FIG. 1(A), a firstmultilayer flow microchannel (1) that serves as a reaction/extractionarea and a second multilayer flow microchannel (2) that serves as adecomposition/removal area may be arranged on two positions of the samesubstrate; then, the multilayer flow microchannels (1) and (2) may becommunicated by way of a guide microchannel (3).

[0039] Further, at each multilayer flow microchannels (1) and (2),channel means (1A) and (2A) for supplying a liquid and channel means(1B) and (2B) for discharging a liquid are provided, respectively.

[0040] For example, in the structural example of FIG. 1(A), a system forselectively analyzing Co (Cobalt) in a sample containing Co ion andother metal ions may be constructed, as illustrated in FIG. 1(B). “N.N.” in the Figure represents 2-nitroso-1-naphthol. In this example, Co²⁺in the sample is extracted to the m-xylene phase as a complex at thereaction/extraction area, and at the decomposition/removal area, metalions other than Co²⁺ are removed and only the content of Co²⁺ isselectively detected by the thermal lens microscope.

[0041] In the reaction/extraction area of the first multilayer flowmicrochannel (1), a liquid/liquid interface of an aqueous/organic phaseis formed and in the second multilayer flow microchannel (2), interfacesof three layers, i.e. hydrochloric acid-aqueous phase/m-xylene-organicphase/strong base-aqueous phase is formed.

[0042] As described above, the invention of the present applicationprovides a system which enables the continuous performance of aplurality of operations at high efficiency, and is thus very useful formicroanalysis, precise chemical synthesis and the like.

[0043] Further, as illustrated in FIG. 2, a plurality of unit operationsmay be carried out in a single multilayer flow microchannel (4). Forexample, as shown in FIG. 2, a plurality of unit operations such as: 1)mixing/reaction; 2) confluence of phases; 3) extraction; and 4) phaseseparation may be performed.

[0044] In the example of FIG. 1, a case in which the first multilayerflow microchannel (1) communicates with the second multilayer flowmicrochannel (2) by way of a guide microchannel (3) on the surface ofthe same substrate is described. However, the multilayer flowmicrochannels (1) and (2) do not necessarily have to be arranged on asurface of one substrate. For example, as in a chip structure wherein aplurality of substrates and intermediate plates are laminated toconstitute a multilayer structure, such as that exemplified in FIG. 3 inwhich substrate (A), substrate (B) and cover plate (C) constitute amultilayer structure, the multilayer flow microchannels (1) and (2), thechannel means for supplying a liquid (1A) and (2A), the channel meansfor discharging a liquid (1B) and (2B) may be configured in athree-dimensional manner. Further, the multilayer flow microchannels maybe communicate with another multilayer flow microchannel by way of aguide hole (5) that vertically penetrates through the substrates andintermediate plates, instead of a guide microchannel (3) arranged on thesame substrate surface.

[0045] In the invention of the present application, one of the keyfeatures is the formation of a multilayer flow involving an interfacewithin a microchannel. The microchannel itself may generally be formedby processing means of various types, including known means such asphotolithography and wet etching. With regard to the substrate,substrates of various types, for example, those made of materials suchas glass, silicon, resin and the like may be employed.

[0046] Regarding the dimension of the microchannel, generally, the widththereof may be around 500 μm or less, and the depth thereof may bearound 300 μm or less, and may be determined in accordance with theobject and application of the multilayer flow microchannel structure.

[0047] Further, a microprojection may be formed at the bottom of themicrochannel, at a position substantially corresponding to the positionsof the parallel interfaces of the fluids forming the multilayer flow,and extended toward the flow direction; this microprojection iseffective for forming a complete multilayer flow with stable interfaces.This projection can be formed as ridges along the flow direction by anetching operation.

[0048] Furthermore, with regard to the multilayer flow involvinginterfaces of fluids, the above-mentioned dimension of the microchannel,the flow rate within the microchannel and the flow amount can beestablished in accordance with the type and the composition of thetarget fluid. According to the knowledge obtained by the inventors ofthe present invention, the surface tension of the fluid primarilyeffects the formation of the multilayer flow involving the interface offluids; thus, the conditions for operating the microchannel multilayerflow system may be optimized taking in consideration such viewpoints.

[0049] Hereinafter, the aforementioned embodiment of the presentinvention will be described in further detail through the followingExamples. It should be noted that the present invention is notrestricted by these examples.

EXAMPLES Example 1

[0050] A microchip with the multilayer flow microchannel 9 having thechannel pattern illustrated in FIG. 1(A) was produced.

[0051] In the production of this microchip, microchannels were formed ona Pyrex glass substrate (3 cm×7 cm) by conventional photolithography andwet etching methods. In FIG. 4 showing the channel pattern of FIG. 1(A),the channels illustrated by solid lines were each formed asmicrochannels having a width of 50 μm and a depth of 20 μm. The channelsillustrated by dotted lines were each formed as microchannels having awidth of 140 μm and a depth of 20 μm. The channels illustrated bychained lines were each formed as microchannels having a width of 90 μmand a depth of 20 μm.

[0052] Among the above-described microchannels, the microchannelsillustrated by dotted lines each have a guide structure formed at theirbottom. The guide structure is provided for stabilizing the interlayerportion of the multilayer flow, i.e., the liquid/liquid interface, andhas a structured as shown in FIG. 5. Overall, at the bottom of themicrochannel whose dimension is 140 μm width and 20 μm depth, two ridgeshaving a height of 5 μm are arranged, and the presence of these tworidges cause the three-layer flow of liquid to be formed in a morestable manner.

[0053] The above-described structure, in which a liquid multilayer flowis stabilized by the projecting ridges formed at the bottom portion ofthe microchannel is a novel proposal by the present inventors and isvery unique as well as significantly effective. By using the thusproduced microchip, Co(II) was selectively analyzed as shown in FIG.1(A).

[0054] A sample aqueous solution containing Co(II) (containing 1×10⁻⁶ MCu(II) and 0.2 to 1.5×10⁻⁷ M Co(II)), a 3.4×10⁻⁴ M solution of2-nitroso-1-naphthol (NN) containing NaOH, and m-xylene, were eachintroduced to the channel means for supplying liquid (1A) from separatesupply inlets. Hydrochloric acid and an aqueous solution of NaOH wereeach introduced to the channel means for supplying liquid (2A).

[0055] In the reaction/extraction area, Co(II) in the sample was reactedand extracted to the m-xylene phase as a complex, and in the followingdecomposition/removal area, Cu(II), i.e., the metal ion other thanCo(II), was removed; thus, only the content of Co(II) in the m-xylenephase was detected by the thermal lens microscope.

[0056]FIG. 6 illustrates a state of liquid/liquid multilayer flowformation, by photograph. The photographs show the status at thefollowing sites:

[0057] (a) Junction point of aqueous phase and m-xylene phase

[0058] (b) Phase-separating point

[0059] (c) Junction point of HCL phase, m-xylene phase and NaOH aqueousphase

[0060] (d) Three-layer flow

[0061] It was confirmed that a very stable multilayer flow was formed inthe microchannel.

[0062]FIG. 7 shows the relationship between the distance from thejunction point of FIG. 6(c) to the position at which measurement bythermal lens microscope was conducted, and the intensity of signalsdetected by the thermal lens microscope, for an aqueous samplecontaining Co(II) (1×10⁻⁷ M) and Cu(II) (1×10⁻⁶ M). The white squarepoints in FIG. 7 represent signals of Co(II), and the black round pointsrepresent signals of Cu(II). From the measurement results obtained at apoint approximately 1 mm from the junction point, it was determined thatCo(II) was selectively detected.

[0063] Further, FIG. 8 shows the relationship between the distance fromthe aforementioned junction point (c) to the position at whichmeasurement by thermal lens microscope was conducted, and the intensityof signals detected by the thermal lens microscope, in samples havingdifferent Co(II) concentrations (the concentration of Cu(II) wasunchanged: 1×10⁶ M)

[0064] It can be seen that the Co(II) concentration was accuratelyreflected on the signal intensity.

[0065]FIG. 9 shows the relationship between the Co(II) concentration andthe signal intensity of the thermal lens microscope obtained based onthe aforementioned results, and exhibits excellent correlation.

[0066] Thus, all of the chemical operations necessary for Co analysiswere successfully integrated and ultramicroanalysis of Co amongcoexisting metals was successfully achieved.

[0067] Further, it was confirmed that the multilayer flow microchannelsystem of the present invention is extremely effective.

[0068] Furthermore, it was confirmed that: when a guide structureconsisting of a microprojection that substantially corresponds to theposition of the interface is formed at the bottom of the multilayer flowmicrochannel, in the reaction/extraction area of the first half of theprocess, the aqueous/organic interface is formed in a stable manner, andin the second half of the process leading to the washing area, theaqueous solution and the extraction phase is completely separated; thus,only the extraction phase is introduced to the washing area and bybringing an aqueous solution of hydrochloric acid and an aqueoussolution of sodium hydroxide into contact with the extraction phase fromthe both sides thereof, a multilayer flow involvingaqueous/organic/aqueous phase interfaces (a three-layer flow) issuccessfully formed in a more stable manner.

Example 2

[0069] The microchannel pattern shown in FIG. 10(A) was formed on aglass substrate by wet etching. The reference numbers 1, 2, 3 and 4represent the fluid inlet parts and 5 represents the fluid dischargepart. Further, symbols a and d in the figure each represent a fluidjunction region, and a microchannel multilayer flow was formed between aand d, as well as on the downstream side of d. The distance between aand d was 18 cm. The width of the microchannel in which a multilayerflow was formed was 70 μm, and its depth was 30 μm.

[0070] The incident angle at which the flows join at the junction regionpoint a was 18°. The incident angle at the junction region point d was280. The radius at point c was 1 mm.

[0071] In the above microchip consisting of microchannels formed on asubstrate, from inlet 1: water (flow rate 5 μl/min);

[0072] from inlet 2: acetone (flow rate 3 μl/min); and

[0073] from inlet 3: water (flow rate 5 μl/min) were each introduced,and the flow rate between point a and point d was set at 13 cm/s. TheReynolds number was or less and the fluids formed a multilayer flow.

[0074]FIG. 10(B) is a photograph showing the formation of a WAW(water/acetone/water) multilayer flow at the junction region of point a.FIG. 10(C) shows the WAW multilayer flow at point b which is located 10mm downstream of point a.

[0075] Next, a microchannel multilayer flow was formed by usingethylacetate in place of acetone.

[0076] From inlet 1: water (flow rate 3 μl/min);

[0077] from inlet 2: ethylacetate (flow rate 5 μl/min);

[0078] from inlet 3: water (flow rate 3 μl/min); and

[0079] from inlet 4: water (flow rate 3 μl/min)

[0080] was introduced and the flow rate between point a and point d wasset at 11 cm/s. A WEW (water/ethylacetate/water) multilayer flow wasformed and the thickness of the ethylacetate layer was determined to be15 μm.

[0081]FIG. 10(D) shows the formation of WEW multilayer flow at thejunction region of point a; FIG. 10(E) shows its state at point b; FIG.10(F) shows its state at the curved point c; and FIG. 10(G) shows thestate of WEW multilayer flow formation at the junction region point d.

Example 3

[0082] A multilayer flow microchannel with a width of 200 μm and a depthof 30 μm was formed on a glass substrate by wet etching. Using amicrochip in which this microchannel was formed, the center m-xylenephase was sandwiched between two aqueous phases containingCo-dimethylaminophenol (CoDMAP) complex, as illustrated in FIG. 11(A),whereby a three-layer flow of aqueous phase/organic phase/aqueous phasewas formed and extraction of CoDMAP to the m-xylene phase was effected.

[0083] The concentration of CODMAP in the aqueous phases was set at6.5×10⁻⁶ M. Further, the flow rate of the aqueous phase was set at 0.5μl/min, the flow rate of the organic phase was set at 1.0 μl/min, andthe flow rate in the entire microchannel was 2.0 μl/min (0.56 cm/s).

[0084] The concentration of CODMAP in the m-xylene organic phase wasdetected by using a thermal lens microscope system (TLM).

[0085]FIG. 11(B) exemplifies the relationship between the distance X inFIG. 11(A) and the intensity of TLM signals.

[0086] It was confirmed that the extraction of CODMAP had reached astate of equilibrium when the distance X was 1.5 cm, in other words,three seconds after the junction. These results suggest that this was anextraction operation of high efficiency.

Example 4

[0087] In a multilayer flow microchannel having a width of 200 μm and adepth of 30 μm, which was prepared in a manner similar to that describedin example 3, a five-layer flow ofbutylacetate/water/butylacetate/water/butylacetate was formed andconfirmed.

[0088] Further, a three-layer flow having a gas/liquid interface ofwater/air/water was also formed and confirmed. FIG. 12 is a micrographshowing the state of such three-layer flow.

INDUSTRIAL APPLICABILITY

[0089] As described in detail above, the invention of the presentapplication provides a highly integrated structure of multilayer flowmicrochannel, which enables the efficient performance of high-accuracymicroanalysis, precise chemical synthesis or the like by continuousoperation of a plurality of unit operations on a microchip, as well as anovel system for operating a multilayer flow.

1. An integrated structure of multilayer flow microchannel, whichcomprises a plurality of microchannels in which parallel multilayer flowthat involves the interface of fluids is formed, arranged on variouspositions of a substrate, wherein each of the multilayer flowmicrochannels is communicated with another multilayer flow microchannel.2. The integrated structure of multilayer flow microchannel of claim 1,wherein the plurality of multilayer flow microchannels are arranged on asurface of one substrate and each multilayer flow microchannelcommunicate with another multilayer flow microchannel by way of a guidemicrochannel that identifies a specific fluid.
 3. The integratedstructure of multilayer flow microchannel of claim 1, wherein aplurality of substrates are laminated, and the multilayer flowmicrochannels are arranged on surfaces of different substrates, andwherein the vertically configured multilayer flow microchannelscommunicate with another multilayer flow microchannel through avertically penetrating guide hole for transporting a fluid.
 4. Theintegrated structure of multilayer flow microchannel of claim 1,comprising a plurality of substrates that are laminated, wherein achannel for supplying a fluid to the multilayer flow microchannel and achannel for discharging a fluid from the multilayer flow microchannelare each arranged on the surface of the same or different substrate asthat on which the multilayer flow microchannels are arranged.
 5. Theintegrated structure of multilayer flow microchannel of claim 1, whereina plurality of multilayer flow microchannels are configured as differentunit operation regions.
 6. The integrated structure of multilayer flowmicrochannel of claim 1, wherein at least one multilayer flowmicrochannel is configured as an analysis region.
 7. A method formultilayer flow operation, which comprises the use of the integratedstructure of multilayer flow microchannel of claim
 1. 8. The method formultilayer flow operation of claim 7, wherein a multilayer flowinvolving gas/liquid fluid interface is formed within the multilayerflow microchannel.
 9. The method for operating multilayer flow of claim7, wherein a multilayer flow involving three or more fluid layers isformed within the multilayer flow microchannel.
 10. A method formultilayer flow operation, which comprises the formation of a multilayerflow of three or more layers involving interfaces of fluids withinmicrochannels arranged on a substrate.
 11. A method for multilayer flowoperation, which comprises performing a plurality of unit operations byway of the interface of fluids in a multilayer flow of three or morelayers involving interfaces of fluids.